1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus.
2. Description of the Related Art
An electrophotographic image forming apparatus is repeatedly subjected to each of the processes such as charging, exposure, developing, transferring and cleaning. The surface of an electrophotographic photosensitive member is required to have high lubricity to a member in contact with the surface of the electrophotographic photosensitive member, such as a cleaning blade for removal of transfer residual toner.
In order to solve the problem of lubricity, a method for adding silicone oil such as polydimethyl siloxane to the surface layer of an electrophotographic photosensitive member is proposed in Japanese Patent Application Laid-Open No. H07-13368.
On the other hand, a charging member in contact with the electrophotographic photosensitive member at a predetermined contact pressure and driven to rotate on a steady basis in an electrophotographic image forming apparatus is required to be stably driven to rotate on a steady basis even when the lubricity of the electrophotographic photosensitive member is increased.
A method for reducing the area substantially in contact with an electrophotographic photosensitive member by increasing the surface roughness of a charging member is proposed in Japanese Patent Application Laid-Open No. 2012-42700 from the viewpoint of preventing the electrophotographic photosensitive member from being shaved off.
However, the present inventors examined the electrophotographic photosensitive member and the charging member described in Japanese Patent Application Laid-Open No. H07-13368 and Japanese Patent Application Laid-Open No. 2012-42700, and found the following problems. Namely, the combination of an electrophotographic photosensitive member having lubricity and a charging member containing large-size particles in a coating layer easily caused micro slips between the electrophotographic photosensitive member and the charging member when the electrophotographic photosensitive member and the charging member in contact with each other were rotated. Consequently, an image defect, i.e. horizontal micro striped image (hereinafter referred to as “banding image”), occurred in the output image in some cases.